1. Field of the Invention
The present invention relates generally to carboxy modified vinyl ester urethane resins, to methods of preparing said resins and to compositions containing said resins. More particularly the invention relates to carboxy modified vinyl ester urethane resins having the following general formula: EQU B--I[A--M--A--M].sub.n --CO.sub.2 H
wherein
A is a radical derived from a polyoxyalkylene bisphenol A; PA1 M is a radical derived from a dicarboxylic acid or an anhydride thereof; PA1 I is a radical derived from an isocyanate having an isocyanate functionality of at least 2; PA1 B is a radical derived from a hydroxyl-terminated ester of acrylic or methacrylic acid; and PA1 n is an integer equal to from 1 to about 10. PA1 A is a radical derived from a polyoxyalkylene bisphenol A; PA1 M is a radical derived from a dicarboxylic acid or an anhydride thereof; PA1 I is a radical derived from an isocyanate having an isocyanate functionality of at least 2; PA1 B is a radical derived from a hydroxyl-terminated ester of acrylic or methacrylic acid; and PA1 n is an integer equal to from 1 to about 10. PA1 X is halogen or methyl, PA1 a is an integer equal to from 0 to 2, and PA1 m and n are integers each of which is equal to at least 1 and the sum of which is equal to from about 2 to about 16. PA1 R' is an alkylene group containing 2-4 carbon atoms, and PA1 n is an integer equal to from 1 to about 3.
The resins may be prepared in addition to other methods by reacting a polyisocyanate and a hydroxyl-terminated ester of acrylic or methacrylic acid with the condensation product prepared by reacting a polyoxyalkylene bisphenol A with a dicarboxylic acid, anhydride or mixtures thereof. The resins are particularly useful in sheet molding compounds made by reaction with magnesium oxide as thickening agent when blended with unsaturated monomer, unsaturated resin, low profile agents, fillers and reinforcing agents.
2. Description of the Prior Art
Noncarboxy modified vinyl ester urethane resins are known and disclosed in U.S. Pat. No. 3,876,726. Thermosetting vinyl ester resin compositions which contain reactive carboxylic acid groups are also known and disclosed in U.S. Pat. No. 3,466,259. Other vinyl ester resins containing reactive carboxylic acid groups are disclosed in U.S. Pat. No. 3,548,030 and U.S. Pat. No. 4,197,390. However, none of the prior art resins disclosed resemble those of the instant invention. Additionally, it has been surprisingly discovered that the carboxy modified resins of the present invention provide for superior properties of compositions containing magnesium oxide.